I am completing the process of stripping my hull. I have used
chemical stripper and sanding. I am now beginning the process of
filling in gouges, chips and low points. I plan to use Marine Tex
for the dents, cracks, gouges, etc. I am thinking of using VC-17M to
cover the bottom, as I will be keeping the boat on the trailer for
this year at least and don't expect a fouling problem. I am looking
more for a hard, slick bottom to maximize performance, and that
supposedly is easy to maintain as soft growth has problem clinging to
the slick surface and wipes off relatively easily.
Roger, you are into the go-fast mode, so I am especially interested
in your opinion, but welcome any and all others to kick in. My boat
was a saltwater boat and as I stripped the bottom I found numerous
small holes in the gelcoat. It appears that this boat had barnacles
and someone scraped them off, taking the gelcoat with them. The
sanding has faired the edges a bit, but I still have a lot of shallow
filling and fairing to do.
Paul Lapointe
I've never used Marine Tex, though they advertise it as OK for below
the waterline applications. I prefer using the WEST System line of
epoxy products, manufactured by the Gougeon Brothers, because you
have complete control over the additives and viscosity. In addition,
using the WEST System, you can apply an un-thickened "prep coat" of
epoxy to ensure a permanent bond between the patch and the hull.
With a prep coat, the properties of the patch material can be
optimized without worrying about the patch/hull adhesion. The
performance of Marine-Tex has been compromised because it's meant to
be used without a prep coat and they do have to worry about adhesion
to the hull.
You didn't say how large the "holes" in your gelcoat were. I would
sand them down to sound fiberglass, feathering out the edges.
Thoroughly clean the cavity with acetone or methyl ethyl ketone (MEK).
Then, I would do a prep-sealing step using WEST 105 Resin and 205
Fast Hardener. Paint a thin coat on with a foam brush. This coat
will cure enough to proceed in about 15-20 minutes. You want the
prep coat to be "green" but not fully cured.
For a final filler material, use WEST 105 Resin, 205 Fast Hardener
and either 410 Microlight Filler or 422 Barrier Coat Additive. Mix
the resin and hardener first, and then add filler until you achieve a
workable viscosity. You want something with the about the viscosity
of the Marine-Tex putty or perhaps a little stiffer so it won't sag
when you apply it. Trowel that into the prepped holes. The stuff
does not shrink as it cures, so try to get the surface as fair and
level with the rest of the gelcoat as possible.
It will be ready for sanding in about 30 minutes give or take a
little depending upon temperature and hardener concentration. The
filled material will bond with the still "green' prep coat of un-
thickened epoxy on a molecular level. The prep coat will have seeped
into the pores in the fiberglass.
Basically, this patch is permanent! If you use the 422 Barrier Coat
Additive, it will actually be stronger, more flexible, more water
resistant and more abrasion resistant than the gelcoat around the
patch.
For final fairing, you need to learn about a hand tool called "The
Long Board". Wrap a full sheet of sand paper around the middle of a
3-foot 2 X 4 and secure with tape or staples on the backside. Sand
with the long board. You will be amazed how easy it is to sand the
patch absolutely fair and smooth. You will know when you are done
when your bare fingers can't detect the edge of the patch when you
run them lightly down the hull and you can't see any ripples, wows,
or bumps when you put your cheek against the hull and sight down it
over the patch from about 3 feet up the hull. This standard implies
a match to better than +/-5 microns!
At this point, stop removing material and start using progressively
finer grades of sand paper. Finish with a final wet sanding of #400
grit wet/dry sand paper, a final high pressure fresh water rinse, dry
with a clean tack cloth. Now you are ready for bottom paint. I use
VC-17M bottom paint on Dynamic Equilibrium. It's OK for relatively
non-fouling freshwater conditions. I would think you'd probably want
something more aggressively toxic in salt water. Ask around your
area to see what other sailors are using. I like to put on two coats,
each a different color so I can tell when the bottom paint is
wearing thin.
Roger Pihlaja
S/V Dynamic Equilibrium
Roger, thank you so very much for all the great information,
directions and detail. Never having used VC-17M before, I was not
sure but after your thoughtful response I am going to try it. I will
be sailing in freshwater so should have little fouling problems,
especially as I will be dry storing the boat this season. You sold
me on the WEST system over Marine Tex. I used to do some glass work
years ago, blue collar side of the operation, so feel comfortable
working with resins and hardeners etc. Again, thank you for the
insight and information.
Paul L
I have used West system epoxy for restoration of my Rhodes Bantam.
The plywood hull has been completely sealed with 3 coats of epoxy.
The last coat had the moisture barrier additive that is powdered
aluminum. That coat was so hard that sanding it back was like trying
to sand quartz. The stuff is easy and consistent to work with though.
For spot repairs, the fast hardener is fine. If you are working over
large areas and want to mix and use larger batches at one time, I
recommend the #209 tropical hardener. It has a much longer useful pot
life, especially in warm weather. Roger's suggestion about long
board sanding is good too. I found hand sanding with a long board to
be easier and more productive than with a power sander. For curved
hull sections, something thinner and more flexible than a 2x4 is
desirable so it conforms to the hull curvature. I used a 1 x 4
spruce plank with handles attached at each end with countersunk
screws. Also use the premium grade wet or dry sandpapers sold by
body shop supply houses and wet sand with soapy water.
Requires a lot less work and the results are more uniform.
Razz
14 April 2000
Hey Razz, almost done with the sanding and fairing. Found a plastic
tool I used a few years ago when working on my son's car. It is
plastic and takes a sheet of sandpaper lengthwise. It has two handles
and conforms to the curves really well. Been happy with the results
so far.
If the weather holds, plans are to shoot the bottom this weekend.
The VC Performance two part epoxy paint I intend to use says you can
use a pressure cup or suction cup to shoot the paint and for small
areas or touch up use a roller or brush. I just hope my Wagner
airless spray gun is up to the task. I'll shoot the keel first to
get the feel for it again and see if it works ok. If not I'll stop
and go rent a compressor and gun.
Anyone have any experience in this area? I chose the Performance
over the 17M because of color. I want to keep the bottom white.
Will dry sail, so growth is not a major consideration.
Paul Lapointe
28 Apr 2000
Sounds like you have made good progress. I have always used a roller
for applying epoxies. I did use a Wagner sprayer for the Pettit
Easypoxy, which is a single-part polyurethane reinforced enamel. It
worked fine.
To be safe, be sure to wear a respirator with organic vapor filters,
all this stuff is very toxic. Keep it off your skin too. Be sure to
spray some acetone through the gun after each batch until it sprays
clear. If epoxy sets up in the sprayer, it's history.
I'm getting ready to haul my boat and send the standing rigging and
halyards off for replacement. Decided to use Sailing Services in
Miami as they are said to supply the very best grade 316 stainless
wire and use the strongest, most corrosion resistant swaging
procedures. They have to, for rigging to last well in tropical salt-
water climates. My bottom is in great shape and I had the centerboard
done last fall. So its rigging upgrades this year. I have added a
Spinlock luff feeder to make raising the mainsail easier.
Next is replacing missing vang tackle, Cunningham hook and line, and
jiffy reefing lines. All the hardware for these is in place but the
rigging is gone. Lazy jacks and a mainsail cover are next. I am
debating replacing the topping lift with a Boom Kicker.
Razz
